Conventional surgical staplers are manually operated, which imposes a high physical requirement for a surgeon to operate. For example, hard manual work can reduce surgeon's focus on other important points like positioning of the device, compression of tissue etc. An electrically powered drive system was thus developed to address this problem. For example, U.S. Pat. No. 8,028,885 proposes to drive a surgical stapler based on a motor-driven leadscrew mechanism. However, the leadscrew produces a drive force that is constant independent of the travel of the surgical stapler. In order to ensure a large force at the end of the travel of the surgical stapler, the leadscrew has to provide a large drive force through the entire range of travel. As such, the motor has to maintain a high output torque and therefore has a low efficiency.